q vs. delta H

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Jada Brown 2H
Posts: 100
Joined: Sat Aug 17, 2019 12:15 am

q vs. delta H

Postby Jada Brown 2H » Mon Jan 27, 2020 4:24 pm

What is the difference between q and delta H? What are the units?

Brian_Ho_2B
Posts: 221
Joined: Fri Aug 09, 2019 12:16 am

Re: q vs. delta H

Postby Brian_Ho_2B » Mon Jan 27, 2020 5:06 pm

q is the transfer of heat (thermal energy specifically) and delta H is change in enthalpy, which is equal to change in the system's internal energy added to internal pressure times change in volume. The full equation for delta H = w + q + P*delta Volume.
If pressure is the same on the outside and inside and that no work is done on the system, then delta H = q. The units of both can be joules or kJ.
Last edited by Brian_Ho_2B on Sun Feb 02, 2020 1:52 pm, edited 2 times in total.

Eileen Si 1G
Posts: 120
Joined: Fri Aug 30, 2019 12:17 am

Re: q vs. delta H

Postby Eileen Si 1G » Mon Jan 27, 2020 9:45 pm

q is the amount of heat that is transferred into or out of a system and is measured in J (joules). delta H is the change in enthalpy of a system and is measured in kJ (or J) * mol-1.

Lauren Tanaka 1A
Posts: 109
Joined: Sat Aug 17, 2019 12:18 am

Re: q vs. delta H

Postby Lauren Tanaka 1A » Mon Jan 27, 2020 10:00 pm

The difference between q and ∆H is that q is the amount of energy transferred in or out of the system and ∆H is the total change in enthalpy of the system.

Micah3J
Posts: 100
Joined: Tue Oct 08, 2019 12:16 am

Re: q vs. delta H

Postby Micah3J » Mon Jan 27, 2020 10:55 pm

Why in the notes are they referred to as equal then?
qp = delta H = n(Cp)(delta T)

Leila_4G
Posts: 114
Joined: Sat Sep 14, 2019 12:17 am

Re: q vs. delta H

Postby Leila_4G » Tue Jan 28, 2020 7:52 pm

And -q means heat out of the system and into the surroundings, right?

alicechien_4F
Posts: 104
Joined: Sat Jul 20, 2019 12:15 am

Re: q vs. delta H

Postby alicechien_4F » Tue Jan 28, 2020 8:18 pm

Leila_4E wrote:And -q means heat out of the system and into the surroundings, right?


-Q means exothermic reaction, so the system loses heat while the surroundings gain heat, making it appear warmer.


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